Alloy steel articles



Patented Nov. 12, 1940 UNITED STATES PATENT OFFICE ALLOY STEEL ARTICLES Vsevolod Nicholas Krivobok, Pittsburgh, Pa., assignor to Rustless Iron and Steel Corporation,

a corporation of Delaware No Drawing.

Original application January 20,

1934, Serial. No. 707,612. Divided and this application October 19, 1937, Serial No. 169,909

1 Claim.

chromium-ni-cke1 irons and steels, more especially high-temperature duty irons and steels of the class indicated, and to articles and manufactures 'of the same.

Among the objects of my invention is the production of reliable, eiiicient and relatively inexpensive high temperature duty alloy irons and steels, which are strong, tough, ductile and readily workable, as by hot or cold rolling, forging, piercing, upsetting and the like into sheet, strip and bar stock, which readily lends itself to a variety of forming and working operations, such as machining, punching, blanking, deep-drawing,

spinning and welding to achieve a variety of tubular products or manufactures.

The invention accordingly consists in the combination of elements, composition of ingredients and mixture of materials, and in the articles, products and manufactures thereof, as described herein, the scope of the application of which is indicated in the following claim.

As conducive to a clearer understanding of certain features of my invention it may be noted at this point that the austenitic chromium-nickel irons and Steals (irons and steels containing approximately 10% to 25% chromium, 7% to nickel, and the balance substantially iron) are useful in the production of a great many cor-, xrosion-resistant and mildly heat-resistant products or articles of manufacture. These alloyirons and steels, especially the la- 8 irons and steels (irons and steels containing 18% chromium, 8% nickehand the balance substantially iron) and the various products, articles and manufactures thereof are used in an increasing number of interior and exterior architectural applications, such as decorative trim, fixtures and ornaments where permanently bright metal resistant to the common corrosive effects of atmospherioconditions is required. Likewise, these irons and steels are employed for agreat many kitchen, dairy, hospital and like applica4:ions, as in cooking and serving utensils, containers and applianceswhere bright metal resistant to rust, stain and other discolorations is required. These 'austenitic irons and steels have also found favor in a number of chemical industries where equipment, apparatus and appurtenances resistant to corrosive attack atroom' temperature or mildly elevated temperature conditions are required.

These chromium-nickel irons and steels, how-- perature duty over long periods of continuoususe ever, they not be reliably and efficiently employed under high temperature operating conditions, and especially such operating conditions in the presence of acids, alkalies, salts, or other agents fostering corrosion and chemical attack. 5

One of the objects of my invention is the production of tough, ductile and durable irons and steels of long life under high temperature operating conditions, which may be readily worked. or formed into a variety of high heat-resistant tubular articles, products or manufactures especially adapted to withstand long periods of continuous operation at high temperatures and under the many corrosive conditions of actual practical use.

Referring now more particularly to the practice of my invention, alloy iron or steel analyzmg approximately 13% chromium, 8% nickel, 1% to 2.5% molybdenum, 1% to 2.5% copper,

2% to,5% manganese, .03% to .4% carbon, and the balance substantially iron, with the usual percentages of silicon, sulphur and phosphorus is produced in a suitable manner, as for example as described in Patent No. 1,925,182 of Alexander L. Feild, entitled Process for the manufacture of rustless iron. The percentages of molybdenum and copper are perfectly maintained at about the "same values, with the sum of these percentages ranging between 2% and 5% in order to achieve good corrosion-resistant characteristics for a wide variety of corrosion fostering agents, such as various acids, alkalies andsalts. The percentage of manganese is preferably maintained equal to the sumof the percentages ofmolybdenum and copper in order to maintain favorable working or forming characteristics of the, metal with maximum life under high temperature operating conditions in the presence of corrosive liquids, fumes,

gases and the like.

In the production of my alloy iron and steel the metal is first produced as ingots which are fashioned into blooms or billets in accordance with known methods and conveniently hot rolled into sheet bar and strip bar sizes. These bars are then annealed and pickled and, for example, cold rolled into sheet or strip of desired thick ness and subsequently fabricated into tubular articles as noted below. My alloy iron and steel corrosion-resistant. and heat-resistant, with.- standing the exacting conditions of high temwithout grain growth, fatigue or failure. For ex ample, ,a bar of this austenitic-chromium nickel iron analyzing approximately, 18% chromium,

8% nickel, 1.5%, molybdenum, 1.5% copper, 3%

life of about 150 hours. Ordinary 18-8 chromiumfnickel iron analyzing approximately, 18% tchr'omium, 8% nicke1, ,07% carbon, and the balance-psubstantially iron has a life of only about '12to1 l hours under like conditions of operation. "My austenitic iron or steel, in addition to having a life under extremely high temperature operat- "ing conditions greatly in excess of heretofore known and/or used austenitic irons and steels, is strong, tough, ductile and durable and readily lends itself to piercing to achieve tubes and to a variety of hot and cold operations either from sheet, strip or bar stock. Thus, by punching, blanking, deep-drawing, spinning, upsetting, machining and like operations, followed by certain welding operations where desired, either with the oxy-acetylene torch or with the electric arc (employing. welding-rodsfor the electric welding of approximately the same, analysis as the stock welded), a great many articles, products or man.-. ufactures, suchas tanks, vats, tubing and piping, fluid valves, couplings, fittings, flanges and bolts as employed in boilers, condensers, oil-cracking stills and 1 other high temperature equipment where strength and resistance tofatigue are of outstanding importance, may be efliciently, economically and reliably achieved using well known and familiar working and fabricating methods and equipment. (Welded products, articles or manufactures, are preferably heat-treated in accordance with known methods to establish a fully austenitic condition of the metal after the welding operation iscompleted in order to assure maximum chemical resistance in use.)

Thus, it will be seen that there has been pro-.

vided in this invention an austenitic chromiumtemperature duty over long periods of time and under the many varying conditions of actual, practical use.

My alloy iron or steel and articles or manufactures of the same is especially resistant to the corrosive attack and embrlttling and fatiguing effects at high temperatures of the gases and vapors normally encountered in the atmosphere,

the mineral waters met with in boiler and condenser applications, the sulphur-bearing liquids, vapors and gases handled in the cracking of oils, and like corrosive agents encountered in many modern industries, as more particularly indicated above.

While in the embodiment of my invention illustratively set forth above, an austenitic chromium-nickel alloy containing approximately, 18% chromium, 8% nickel, 1% to 2.5% molybdenum, 1% to 2.5% copper, 2% to 5% manganese, .03% to .4% carbon, and the balance substantially iron, is specifically described, it is to be understood that good results are achieved where the chromium content ranges between and 25% and the nickel content between 7% and In my alloy irons and steels, as in heretofore known and used austenitic chromium-nickel irons and steels, carbon is not present as an essential ingredient.

because of the commercial impracticability to produce metal entirely free of carbon. Although, at the present time, austenitic chromium-nickel steels containing from about .03% to .10% carbon are readily produced commercially, some,

melting practices yield metal with as much as 2%, .3% or even .4% of this ingredient. In my alloy irons and steels, as in known austenitic irons and steels; a carbon content as low'as is commercially feasible is preferably maintained. Ordinarily, and-for most purposes, this amounts to less than .10%.

As many possible embodiments may be made of my invention and as many changes may be made in the embodiment hereinbefore set forth, it is to b understood that all matter described herein is to be interpreted as illustrative, and not in a limiting sense.

I claim:

Wrought alloy austenitic 10 to 25 per cent chromium, 7 to 15 per cent nickel and .03 to .40 per cent carbon, stainless steel tubular articles characterized by their freedom from corrosion embrittlement and by their resistance to the wash and scour of corrosive fluids, used under conditions of high internal pressures and at high temperatures, said characteristics being produced by the inclusion in said alloy steel of 1 to 2.5 per cent molybdenum, 1 to 2.5 per cent copper and 2 to 5 per cent manganese.

VSEVOLOD NICHOLAS KRIVOBOK.

The presence of this element is permitted only 

